Geometric Modeling of Infiltrated Solid Oxide Fuel Cell Electrodes with Directional Backbones

Solid oxide fuel cell electrodes with directional properties have shown their potential to get the maximum electrochemical reaction sites, gas diffusivity and ionic conductivity, simultaneously. New manufacturing methods, like freeze type casting, have used to make this kind on electrodes. In this work, the effect of backbone directional behavior in infiltrated solid oxide fuel cell (SOFC) was simulated. A series of directional backbones were generated by a statistical method and analyzed in regard of available active surface density and phase tortuosity. Different amount of electrocatalyst particles virtually deposited on the surface of those scaffolds. Some geometric parameters like triple phase boundary (TPB) density, active surface density of particles and the pore tortuosity were extracted from those realized models. The simulations showed that the optimum amount of infiltration to get the maximum TPB density or active surface density of impregnated particles can be varied depend on the porosity and geometric anisotropy of scaffolds. Being directional in backbones, normal to the electrolyte, has a positive effect on active electrochemical sites especially active surface density of deposited particles. Also it can improve the gas transport even in low porosity microstructures, but adding electrocatalyst particles may increase the pore tortuosity considerably. Accordingly, directional backbones have the potential of increasing the performance of infiltrated electrodes via adding electrochemical sites and gas diffusivity.